


String Theory at its finest!

by colioli4



Category: The Big Bang Theory (TV)
Genre: Anger, Bisexuality, Clones, Dimension Travel, Doppelganger, F/F, Falling In Love, First Time, Girls Kissing, Horniness, Kissing, Love, Love at First Sight, Moaning, Narcissism, Naughty, Oral Sex, Self-cest, Sex Toys, Time Travel, To Be Continued, Touching, Twincest, Vaginal Fingering, Vibrators
Language: English
Status: In-Progress
Published: 2014-02-26
Updated: 2014-06-03
Packaged: 2018-01-13 20:59:43
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 4,262
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1240642
Author URL: https://archiveofourown.org/users/colioli4/pseuds/colioli4
Summary: <blockquote class="userstuff">
              <p>(Third chapter added!!!)</p><p>Sheldon has finally found a way to prove his String Theory: he has built a gateway in which he can go to another dimension next to our own.</p><p>Accidently, Penny meets the Penny from that dimension, and soon finds out that they both have very naughty and narcissistic feelings for each other. </p><p>And when Amy finds out about the gateway as well, things turn even more weird...</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> I'm a huge fan of The Big Bang Theory, and especially of Penny/Kaley Cuocu.
> 
> And what is better than one single Penny?
> 
> Well, two of them, of course!
> 
> *Update*
> 
> Continuing the story, now with a chapter dedicated to Amy Farrah Fowler(s)!  
> Why should only Penny have all the fun?
> 
> Hope you enjoy it people!

It is one hot summer afternoon when Penny gets back to her apartment building after a hard day of work at the Cheesecake Factory. She climbed the stairs, because, obviously, the elevator still hadn’t been repaired, and she was about to open her apartment door when she first noticed the door of her neighbour's apartment was still partly open. 

'Interesting', she thought, as she knew Sheldon, who was so extremely intelligent it became freaking annoying to everybody, never let his door stand open, in fear of intruders (the most normal fear he had next to his fear of birds, single socks and unsolvable formulas). 

She put her bags down and, still wearing her Cheesecake waitress uniform, walked to the door. Not knowing if anyone was inside, she knocked. When no one answered, she peeked around the door to take a look inside. 

The setting of the apartment was very different than it had been the day before, when she had said goodbye to Leonard, who, together with Rash and Koothropalli, had gone to a physics-thingie-meeting in London. Sheldon had not been invited as, well, he appeared (or maybe even was) a total nutjob at times, and the organization behind the meeting must have known this for a fact.   
'And frankly', Penny thought with a tiny smile, 'he probably is totally insane. Even if his mother had him tested.' 

The couch had been moved back against the wall, and so had the lazy chairs and the tv. Instead, a metal frame stood in the middle of the apartment. 2 by 2 and some ten centimetres thick, it looked a bit like a gate, or a portal ('God, I'm learning too much from these guys', Penny thought). On top of the frame stood something that appeared to be a tesla-reactor ('Seriously, I'm going to kill them for turning me into… this!!!'), but upside down, its top pointed towards the frame. From it, two thick cables ran down each side of the frame, with one headed to one of the many plugs in the apartment, and the other to Sheldon's laptop, which sat on a small picknick table across from the frame. 

Curiosity winning it from her instincts, Penny stepped into the apartment. She walked slowly towards the gate, looking dubiously for its meaning.   
A second later, Sheldon rounded the corner from his bedroom. He halted as he caught sight of Penny. 

"Penny, what are you doing here?" he asked surprised.

"Oh, hi Sheldon", Penny replied as he saw walking towards her", "I umh saw that your door was opened, so I came over to see if you're alright."

Frowning, Sheldon looked at her. "And you come just barging in, while a men could be doing anything at the time that is not to be seen by other's eyes?"

Blushing a bit, Penny asked: "Ehrm... What do you mean by anything?"

Sheldon looked surprised at her and said: "Oh, you know what I'm talking about." Before Penny could give a stuttering answer, he went on: "I could've been working with dangerous chemicals, using radioactive materials, OR I could've been trying to make myself a hot cup of Texas Tomato soup, like my Mima always did". 

Before she could speak, he interrupted her again. "Oh, but you must be wondering what I'm building here!", he exclaimed, happy like a four year old showing his first drawing to his parents, hoping it to be a masterpiece. 

Uncertain of what to say, Penny just nodded. 

"Excellent! I will explain!”. He turned towards the device, and he said, with not a little pride in his voice: “This is an interdimensional-gateway, which, using the String theory I've been working on for the last decade, makes it possible to visit other dimensional pictures of our own. Using the formulas..." and he rattled off on one of his crazy scientific tours, just as Penny had hoped he would finally be able to tell her stuff that wasn’t totally insane.

"Eh, Sheldon, the quick and not-nerdy version please!!!" Penny exclaimed above his going into depth on Newton’s Laws with something of a religious respect.

"Oh... alright... well, it's a gateway to another universe. An almost identical one, next to ours, in the String. So identical in fact, that we will likely not see any difference between theirs and ours. That is what my theory is about, remember? DO YOU UNDERSTAND ME NOW?!?", he yelled the last sentence.

Penny blinked and nodded slowly.

Sheldon smiled his 'smile', which made Penny always seriously think of any of the mad scientists in any movie Leonard had made her watch. 

"Do you want to see me test it?" Sheldon asked brightly. 

"Uhm... well..."

"Oh great!!! Wait here, I'll start it up..."

Knowing she could not dissuade him, and getting increasingly nervous, Penny let the smart scientist walk over to his laptop and type some quick commands in it. Almost immediately the gate started to hum.

"Oh, can you hear that?" Sheldon said dreamily. "That is the sound of scientific progress!!!"

Penny answered with something combining 'Aha' and 'I see', making 'Ahsee'.

The humming grew louder, and blue sparks became visible around the upside-down tesla-reactor. 

"It works! IT WORKS!!!!!!" Sheldon screamed. 

A flash, and the humming fell back to a soft hiss. 

Penny blinked the tears that the bright flash had given her and stared at the gate. It was not an empty frame anymore.   
Through the gate, she could see the apartment. But it was not the part of the apartment that should have been behind the frame. She could see the front door, Sheldon' and Leonard's laptops set on the desk, everything that should have been behind her. It was like she was looking in a mirror of some sorts.

And in that frame, at the same distance she stood from it, was another Penny. The same long, blonde hair set in a tight ponytail. The same green and yellow outfit. The same shoes she had saved for for three months, and wore almost never.

Penny stepped forward, curious, and, at the exact same time, the other Penny did the same. Penny looked into her own beautiful face. She had always known that she was a pretty hot girl. But she had no idea that she was this mesmerizing. The person on the other side of the gateway looked far more pretty than she ever looked in a mirror.   
Her body was lean of all her recent fitnessing. Her low-cut Cheesecake Factory uniform really did flatter her breasts. She and the other Penny turned at the same time and took a good, long look at the others ass. It just looked marvelous. Tight yet curvy.

Penny turned to Sheldon. "Funny Sheldon, making that mirror appear. Nice trick though." 

Sheldon looked multiple times from the frame to Penny and back. He frowned, went to say something, then shut his mouth again. He moved his head a couple of degrees to the right and looked strangely to the blonde girl.

"Ehm... Penny... there is no way in which I could have made a mirror appear out of thin air with some sparkles. I am NOT a magician. That is a real portal to another dimension directly next to ours in the String."

Penny looked at herself in the frame, and then sarcastically back at Sheldon. "Sure Sheldon, and I'm James freakin’ Kirk." (‘Dammit guys!!!’)  
"If you don't believe me, Penny, look at yourself in the portal. You're not mirrored."

Penny looked unbelievingly at Sheldon, then turns to look at the frame. She and her other self blink as the truth starts to dawn on them. They gasp as it hits them squarely in the face. Then, both take a step forward, unable to look away from each other. And another. And another.   
They only stop when they stand just a couple of centimetres away from each other, their breasts close to touching. Slowly, both raise their right hands. Ever so slowly, they touch each other's cheek. 

A ripple seems to go through space and time.

As if stung, both girls jump backwards.

"Wauch, what was that?" yells Penny.

"Shit, I've no idea!" Penny yells back.

Then they turn to each other, surprised. 

"Wow... did we just..."

"... speak without echoing? "

Both girls blink.  
The Sheldon’s both step forward.  
"Mmm... it seems that you touching brought you out of the synch... Intriguing..." Both say, still echoing each other. "You probably still think almost the same, but it does not necessarily have to be the EXACT same at the EXACT same time..."

The Penny's look back at each other. They literary check each other out openly. 

"Damn", Penny thinks, "if I was a lesbian, I'd so do her..."

"Sheesh", Penny thinks, "if I was gay, I'd so fuck her..."

Both subconsiously lick their lips. However, they do not really do it subconsiously. In fact, they both lick their lips at each other.

They freeze and look at each other. Did she just...

Penny winks at Penny.

Penny winks back at Penny.

Then Penny takes a step backwards, and Penny a step forwards. 

Three seconds later, both Penny's have run out of the apartment and into their own, leaving two very confused Sheldons behind.

Sheldon looks at Sheldon with a frown and vice versa.

"Did they just... are they.."

Then they both shake their heads.

"Nah, they wouldn't...” 

"... would they?"


	2. Chapter 2

**Summary for the Chapter:**

> The continuation of the story. And, finally, some hot action...

**Notes for the Chapter:**

> Enjoy!!!

The Penny's entered their lush apartment out of breath of the short sprint and their sudden anxiety.

They stop in the middle of the large living room and gave each other another quick check up. 

"Holy mother of God, I do look gorgeous...", both thought, a smile creeping on their faces.

"Do we really want to do this?" Penny asked. 

"Well, I always wanted to do myself, and sheesh is it long ago that I did a girl...", the other woman answered.

'Mmm, yeah, Sheldon's sister. Wow, that girl could finger...'

Both stare dreamily into the distance for a second before returning their gaze to each other. 

One steps forward and squeezes the breast of her twin playfully. 

“You know, technically, this is masturbation.”

Penny bites her lip and starts fondling with her double’s boob as well.

“Or, it is incest. I don’t really care either way.”, she says with a naughty grin spreading over her face.

"So, then, give me one reason why I shouldn’t fuck you right here, right now."

Penny smirked. "Because I'm going to fuck you first, sweety", she said, as she took another step towards the other blonde woman.

"Right here..." she murmered as the both moved forward and let their bodies touch each other.

"... right now", both whispered just before their lips met.

The kiss was soft but delightful. However, it wasn't enough.  
Far from it.

The kiss grew deeper quickly, both women capturing each other in a loving embrace, forcing them to go even further.

They broke the kiss only to get rid of their Cheesecake Factory tops. Then, they were at it again, lip-locked and touching the other's unveiled breasts.

Their tongues fought for dominance as their hands started to roam through each other's neat buns, loosening them and feeling the golden rivers of each other's hair cascade through their fingers. 

One of the Penny's lowered herself and started to suck on her twin's tit. The other let go of a moan as she felt her own lips playing with her nipple. 

Penny the went further down, stopping only at the other’s bellybutton to stick her tongue in it once, resulting in a shiver of her identical lover. 

When she reached the other's hips, she looked up. Both women were flushed a bright red and were breathing heavily. Penny just nodded and smiled. With one smooth motion, the girl pulled down Penny’s skirt and underwear, revealing what was underneath. Penny looked mesmerized at her own vagina on display just centimetres before her face, growled hungrily, and dug in. 

Penny let go of a tiny yelp as she felt pleasure overtake her. She felt Penny licking and kissing around her entrance, and then stuck her wet tongue into her pleasure spot. 

Her legs started to weaken, so she dropped down of the sofa. Penny followed her every movement, and returned to her work on her own vagina, sitting in front of the girl, who had her legs spread wide open. Penny moaned at ever slight movement the girl made inside her. She had never felt something like this before, never before had she experienced such an amount of pleasure racing through her system. Not from Leonard, not from Missy, and not from any of the other lovers she had had, male or female.

She had always been hard to please, often having to result to her own finger work to be able to come to an orgasm, as the men and women she had slept with had never totally been able to keep up with her. Now, however, it were her own experienced hands going at work on her, and, boy, did she love it.

When she couldn’t hold any longer, she came with a yelp. The other Penny was able to swallow most of her juices at once, but still some of it got past her lips, dripping on the cushions on the sofa and on the floor.

Penny finally understood the trouble her lovers had always had with the amount of fluid she produced when she had her orgasm. It was just too much to be able to swallow all in one gulp. She sat back a bit and after a few tries was finally able to empty her mouth. 

She did enjoy the taste of her own vaginal juices, however. It had some kind of sweet flavor to it, that she somehow found delicious.

Her twin was still sitting on the couch, breathing heavily, and barely conscious of the passionate assault she had just endured. Penny leaned forward and licked the last drops of female cum of the girl, resulting in a soft moan. 

She sat down on the other side of the girl and began to play with the other’s hair. She had always loved her long golden locks, and spent more than an hour every morning getting it in just the right model. That is, when it was a workday or when she had a date. In the weekend, she often let her hair be, too lazy to do anything about it, or pulled it into a tight ponytail or bun to keep it out of her eyes.

Here, however, she could see how gorgeously her golden hair fell around her face and down her shoulders. She whirled a strand around her finger, feeling the softness and smoothness of it with her fingertips.

Penny’s breathing rate slowed down to a more acceptable level and she slowly opened her eyes. Penny let go of her hair and smiled at the identical girl.

“You like it?”

“Best… oral… ever…”, she mutters. She has caught her breath, and is ready for more. 

Her arms reach around her identical lover and hugs her close, bringing their lips together. She groans annoyed as she feels the fabric of the other’s skirt rub against her hips.

“Your turn to undress”, she whispers in the other’s ear as the girl work on her neck.

The other girl groans and stands.

She turns around and starts to show of her body to the other woman as she removes her skirt and string excruciatingly slowly. She licks her lips at her identical lover, who bites her lower one in return. 

As she drops her last piece of clothing on the ground and kicks it away, the other girls raises, a mischievous grin on her gorgeous face. 

“Look what I found…” she whispers sexily, as she reveals a long pink vibrator from behind her back. It had been lying underneath one of the cushions on the sofa from one of her last masturbation sessions, and she had felt and grabbed it when she had come.

“My turn now…”

She pushes the other more than willing girl down on their soft carpet next to the soft seat they had just used. Penny lands on her back and looks up flushed at Penny, who is kneeled in front of her. She spreads her legs and hears the sex toy being turned on. Breathing hard, she leans back and waits for the girl to start on her.

Even if she had expected herself to be prepared for the penetration, she still groans loudly as the vibrating dildo enters her vagina. The constant familiar movement inside her gives her happy reminders of all those times she used her favorite toy to fight her horniness. And now there is a hot, perfect girl sticking it in her pussy with a smile on her face.

She moans as Penny sticks it deeper inside her. The woman gazes with a mischievous look at her.

“You like this don’t ya?”

Penny groans a ‘Yes’ as Penny pushed the vibrator in just a bit harder.

“You like it, when someone is fucking”, she penetrates the girl again, resulting in another moan. “… you. Especially, when that person looks just… like… you.”

She shoves the sex toy deeper and deeper with every pause. Penny cries out in pleasure as the toy grazes her G-spot. 

Then, to her dismay, she feels the vibrator being retracted from her. Her moans in displeasure and looks up angrily at the identical girl in front of her. She had been so incredibly close that the lack of attention was close to torture to her.

Penny looked Penny in the eye and smiled cutely. 

“Beg me”, was the only thing she said.

Penny sighs. She had always been playful when it came to sex, but now that she was at the receiving end, she understood the annoyance some of her partners had shown as she played with them.

“… Please…” she said, but the other woman shook her head.

“Louder.”

“… Please Penny, I…”

“Louder.”

“Penny, pl…”

“Louder I said!”

“PENNY! FUCK ME! I BEG YOU. STICK THAT VIBRATOR UP MY PUSSY AND FUCK ME TILL I COME!!!!!”, Penny screams, losing her dignity and patience.

Penny eyes widen in surprise, then she grins down on her.

“Better.”

She stabs the dildo down into the identical girl before her once more, and she comes.

Hot juices spray all over Penny as the woman orgasms loudly, and Penny wonders if any of her neighbors would have heard their sexual escapades. Then she shrugs. What does she care? 

Penny’s orgasm ends after a minute. She drops back on the soft carpet, her entire body covered in sweat and vaginal fluids. She forces her breathing to slow. 

Penny drops on top of her. Her sweat mixes with her juices that cover most of Penny’s body and face. 

Her identical lover looks hateful at her for the torture she has just endured, but she can’t fight against the absurdness of Penny’s mischievous smile, surrounded by spots of vaginal fluid, and is soon laughing softly as well. She hugs her lover close, pressing their breasts together and kisses her.

The women just continue to lie there, naked, in a lover’s embrace, laughing and kissing together, and both just wonder one thing:

What’s next?


	3. Amy Farrah Fowler X 2

**Summary for the Chapter:**

> (Another chapter in the String Theory Storyline. Please enjoy, and please comment/review whatever you think.)

Meanwhile, in the hallway…

Amy walked up the last flight of stairs, a frown on her face. Since she finally heard the story of how the elevator of the apartment building had crashed, for the most part thanks to Leonard and Sheldon, she knew to whom she had vent her annoyance of always having to climb these damnable stairs, over and over again. And that was exactly what she was planning to do! Her boyfriend should have resolved the question of the fault with the landlord long ago! But before she could knock on the door, it already swung open. And not one, but two Sheldon’s stood in the doorway. Her mouth dropped open and her eyes became wide in surprise. Both man wore the exact same outfit and each looked at her with their head slightly turned to the side, looking questioningly at her. In this way the three of them stood for over a minute, with neither of them speaking a word or moving a finger.  
Then, Amy managed to speak the obvious question: “H… how…?”

“Interdimensional travel using String-Theory.” both said at the same time.

Amy nodded slowly. She could live with that idea. Far more easily than Penny, or anyone else in her friend group, she got over her shock and looked at the problem at hand in a more scientific way. She had no reason to doubt her boyfriend (or was it boyfriendS now?), simply because he wasn't able to lie: his mind didn't let him. 

“So… what are…” she began.

They didn’t let her finish as they pushed their way past her and bounded down the stairs.

“Hey, where are you going?!?” she yelled, running down the first few steps after them.

“To procreate!” they called back.

“What?” Amy yelped in a shocked fashion. “You’re going to have sex… together?”

However, both men were already too far for them to hear her, and a moment later she heard the heavy doors of the apartment building slam shut.

Amy stood there for a long moment, trying to process what just had happened. Somehow, her boyfriend had been able to build a true teleporter of some sort, connected to other dimensions, and had found himself. And, somehow along that way, the two of them had decided to… have sex? Amy frown deepened. She knew of Sheldon’s innate wish to procreate with someone with the same mental abilities as him and create some sort of superhuman, the next step in mankind’s evolution, but she had always thought herself to be that person. And that someday, somehow, the two of them would finally be able to have make that child. But now…

She suddenly felt cold. Her boyfriend had set her aside for the first clone of himself he found, and that did hurt. Anger rose inside her. She suddenly despised Sheldon. His narcissistic ways were the only things important to him, not her. She could as well have been a cute puppy, to be played with and fed, but nothing more than that. Hate and anguish weighed heavier and heavier inside her, and a single tear rolled down her cheek.

And that was when she made her fateful choice.

‘If Sheldon can do it, than so can I!’

Without thinking about any consequences, Amy stormed into Leonard and Sheldon’s apartment. Her other self in the next dimension along the String did the same. They made eye contact, saw each other’s determination, and rushed forward. They smashed together in the middle of the gateway, their bodies colliding with enough force to snuff out an average star, or so it seemed to them. Their lips met and electric currents shot through their bodies as they finally – FINALLY – kissed another human being (the smoking monkey didn’t count as having kissed, and Sheldon’s one tiny little kiss was nothing compared to this). Their hands groped desperately at each other’s breasts, kneading and cupping them, their need for sexual interaction tangible in the air. 

Amy fell backwards through the portal into Sheldon’s living room, pulling her twin with her. The woman landed on top of her and continued the kiss, deepening it by pushing her tongue through Amy’s surprised lips and starting to feel up her clone’s identical orifice. They both growled satisfied as their tongues attacked one another, touching and exchanging saliva while at the same time sending messages of pleasure and bliss through their neurons to each other’s brains with their actions. 

Their hands ruffled through their brown, straight hair. Their breasts rubbed together with every movement, resulting in more identical moans from two different throats. They quickly undressed the upper half of each other’s bodies, revealing perky breasts, with pink, stiff nipples. The silence continued, except for the gasps the women made when they started playing with each other’s boobs. They cupped them, pinched the nipples, gave them a lick once or twice when they had separated after a passionate kiss, everything to pleasure their other selves.

The last clothing was ripped off their bodies by their clone, and both looked entranced at each other’s naked beauty. They both know exactly what they are about to do, and neither can’t wait any longer. They sit down on the floor, open their legs and smash their womanhoods together. Both moan is ecstasy as their wet vaginas smack together. After a minute, they find their rhythm, and they start to hump their hips together. Their eyes keep connected through the tangle of legs, grey gems set in red faces. Their bodies become slick with sweat, as they get closer to their breaking point. Both try to hold on to the pleasure, try to keep their clone’s body as close against theirs as possible. However, it is to no avail. With a loud groan, louder than ever before and filled with so much barely contained pleasure, as if it is the first time for them to orgasm in their entire lives, they come, and their already wet bodies become drenched as they squirt all over each other.  
Their backs arch up as they feel the last traces of energy leave their bodies together with their collective pleasure. They drop back on the floor, their vagina’s still connecting with every laboured breath, and they faint from exhaustion, but not before thinking a simple word: “God…”


End file.
